Jailbroken 6.1.6 iPhone 3GS still No Service?

Hi, some background information: My friend had gotten an iPhone 3GS refurbished and it wasn't locked and worked fine. She was going to give it to me so she reset it, which I think triggered a carrier lock. The phone required a sim card to activate, and it said the sim I put in it (the same carrier she was using with it) wasn't supported. I called Apple and apparently it's locked to some japanese carrier.

What I've done so far: I followed a guide on jailbreaking / unlocking. I used redsn0w and changed the ios to 6.1.6, downgraded the baseband to 5.13.04, and installed ultrasn0w through Cydia. Also the phone uses the old bootrom. Now the phone goes past the initial setup screen and I can use apps, but it still says "No Service" at the top left and I can't send texts or make calls. I just bought the sim card.

I really appreciate any help, it would be a big deal if I actually get this phone to work.

I think when an iPhone gets locked, you can't really do anything without going to the carrier to which the phone is locked. Unless you can magically get data on the device even though it says "no service", you might be nearly SOL.

No judgement, but I would try replacing it with an Apple refurb tied to the correct carrier. You're really pushing your luck running a 3GS today.

I went through something similar when I bought my 3GS years ago from a 3rd party. Turns out it was Canadian on Rogers. Im in the US on AT&T and had to wait until ultrasn0w updated... Total pain. And lost my GPS in the meantime. My advice is to make sure your device will work on your current carrier.